The broad, long-range objective of the Pharmacology Core Laboratory is to provide analytical pharmacology support for those clinical protocols which mandate drug testing for subsequent pharmacokinetic studies. There will be four specific aims: (a) Perform the determination of drug and, if indicated, selected metabolite levels in serum (plasma, or other body fluid) samples from AIDS or HIV positive patients participating in protocols which mandate such measurements; (b) Depending upon protocol requirements, use the results to carry our pharmacokinetic studies locally, or submit the results to an inter-institutional (network) central organization for comparative pharmacokinetic studies; (c) Adopt and/or modify existing analytical methodologies or develop new analytical methodologies to assure that the first specific aim is accomplished by utilizing the most advanced available analytical technology commensurate with the pharmacokinetic goals of the particular clinical protocol; (d) Utilize existing and, if needed, develop new, local quality assurance programs and also actively participate in inter-institutional (network) quality assurance programs for all drugs measured. Providing pharmacokinetic data will be of immediate and direct benefit to patients on ACTH protocols because they will permit adjustments of doses and regimen to increase efficacy and reduce toxicity.